This invention relates generally to complementary metal-oxide-semiconductor (CMOS) output buffer circuits and more particularly, it relates an improved CMOS output buffer which has a higher speed of operation and has a high immunity to noise.
In common practice, it is often required to use more than a single circuit type or logic type in an electrical system. For example, a complementary metal-oxide-semiconductor (CMOS) central processing unit may interface through buses with peripheral units adapted to receive transistor-transistor-logic (TTL) logic levels. Thus, there have been provided heretofore output buffer circuits which enable circuits to receive CMOS logic levels and to provide output signals that are TTL compatible. However, one disadvantage of these prior art output buffer circuits is that they produce output signals which were susceptible to oscillations (inductive ringing) caused by noise on a supply bus line or a ground bus line of an integrated circuit device or cross-talk, thereby reducing its speed of operation and/or causing an erroneous output.
It would therefore be desirable to provide an improved CMOS output buffer having minimal ringing or cross-talk in its output signals. It would also be expedient to provide such a CMOS output buffer which has low propagation delays, thereby rendering a fast speed of operation.